Ok question for you guys. This is the first time it's ever happened...So right at 6K in 3rd gear my exhaust backfires. I read it's because unburned fuel is escaping into the muffler and the heat from the exhaust causes it to explode. Is this a bad thing? Does it mean my fuel ratio isn't up to par?

 

stock exhaust???

 

Thats a good question. I thought it had to do with something like running rich and to much fuel. Maybe its time to throw a 2.9 on there to lean it up a little. I'm not sure though so wait till someone who knows for sure post. I have seen other SS/SC backfire before, never happened to me.

^ He has GMP exhaust as far as I know

 

If you just modded your exhaust that is probably why. I run the GMPP cat back and I get backfire almost every time I rev a gear out near the read line. So its pretty normal, as for the is it ok part, I asked the same thing (of multiple people, including a mechanic) and have been told its not that big of a deal, though if it were large enough back fire it could hurt something (they said thats rather unlikley in a car like this though).
just my .02, hope it helps.

 

No here's what I have:

2.90" Pulley
GM Stage 2
GMP Manifold
GMP Performance Exhaust
XTC Catless DP
AEM Airbox Mod
Torque Dampener

 

im stock and i backfire sometimes, sounds pretty badass IMO

 

yeah sometimes i backfire in first gear

 

Just to make this clear...When you redline the car it makes the popping sound...that isn't backfiring.

 

Ah, its mainly the catless DP. Unless it gets real loud (sounding like a shot gun going off), and just stays to the kinda popping noise it shouldn't hurt anything.


*EDIT*
your posting too quick heh. As far as I know, the popping noise after you get off the gas near redline *is* backfire. Though I think this is quickly going beyond my knowledge, so I'll leave you with what I've said and hope someone who knows exactly what it is jumps in.

 

Here's what it says according to Wikipedia

A Back-fire or backfire is an explosion in the intake manifold, carburetor/throttle body or air cleaner of an internal combustion engine. Although an explosion in the engine's exhaust manifold or exhaust system, is often referred to as a backfire, it is actually an afterfire.

The term was derived from experiences with early unreliable guns which could literally blow up in a shooter's face. From this came the use of the word "backfire", as a verb to indicate something that produces an unintended, unexpected, and undesired result.

Explanation

The terms backfire and afterfire are specific and exclusive. An explosion in the exhaust system is never a backfire. The following information refers mostly to afterfiring. Perhaps a mechanic who has more intimate knowledge of the causes of backfiring & afterfiring can sort out which parts belong where.

Backfire in an automobile engine typically results from various malfunctions related to the air to fuel ratio. Usually, backfiring occurs in carbureted engines that are running lean where the air fuel mixture has insufficient fuel. ("Running lean" is typically a sign of mal-adjusted carburetors or fuel injection where there is not enough fuel for the amount of air). Afterfire occurs in engines that have an emission system malfunction (air injection system diverter valve), exhaust leak or unburnt fuel in an exhaust system in which the catalytic converter has been removed. When a driver shifts up and lets off the accelerator, the engine has a moment of running rich or with insufficient oxygen. This causes an incomplete burn which causes the fumes to explode in the exhaust system. The leak itself is the most dangerous aspect. Without it, the mixture would cool enough not to explode. A fuel injected engine may backfire if an intake leak is present (causing the engine to run lean), or a fuel injection component such as an air-flow sensor is defective.

Common causes of backfires are:
* Timing – If car is distributor-less
* Timing – If a two stroke engine is backfiring every other stroke.
* Fuel pressure, fuel filter and pump – leaks and corrosion could cause lack of fuel during the fuel injection event.
* Bad wiring in ignition – ..if car won't run for more than a few moments.

In older engines, backfiring may be considered normal. Backfire is rare in modern cars with fuel-injection and computer-controlled fuel mixtures.

Common causes of back fires in the intake manifold are bad spark timing, or incorrect (usually lean) fuel ratio.

When starting an engine, timing that is too advanced will fire the spark plug before the intake valve is closed. The flame front will travel back in to the intake manifold, igniting all of that air and fuel as well. The resulting explosion then travels out of the carburetor and air cleaner. A common air filter will allow the gases to escape, but will block the flame front. On many small marine engines, no air filter is used, but a screen is placed over the intake of the carburetor as a flame arrestor to prevent these flames from escaping the intake, and potentially igniting fuel, or fuel vapors in the enclosed sump or bilge of the boat and causing a fire or explosion. Improperly adjusted carburetors that create a lean condition during acceleration can cause the air fuel mixture to burn so slowly, that combustion is still taking place during the exhaust stroke, and even when the intake valve opens. The flame front can then travel up the intake and cause a backfire.

In drag racing, backfires in the intake usually result in the complete destruction of the intake manifold, the carburetors, blower, and sometimes engine.

 

right what he said ^

 

After reading that, if you are truly getting back fire and not after fire, then yes, you have a prolem.

 

Technically speaking it's after-fire but it's commonly referred to as backfire. I just want to know if I need a tune if this is a sign of improper fuel ratios.

 

With out a cat to take out the extra unburnt fuel in your exhaust, your going to have some after fire. You shouldn't need a tune to fix it (as a matter of fact, I doubt you *could* fix it with a tune). I wouldn't be too worried unless its real real loud.

 

Ok cool thanks.

 

^ You my friend are a new member of the fire breather club! I have a friend who has a custom 3" exhaust without cat and he gives out a big ol' flame sometimes.

 

Woot awesome

 

interesting indeed

 

You should actually make a fire breather club!!!!

 

no... it pops around 6k not 6500

 

More like 7000

 

if you at wide open throttle. it should not backfire. meing you are 100% ***** to the wall. if you feel the car lay over suddenly and pick back up, there is some issues that need to be tweeked on through the ecm. aside from this, i have yet {besides mine} find a 42 lb car that doesn't do this randomly.

 

Mine has done it to me twice , at about 6300 in 2nd it popped like hitting the limiter , then pulled to redline . It never threw a code or came up on a tech2 in any way . I thought i hurt the motor somehow but that was about 5K ago.

 

Since you are way down south you should get a custom tune because you put that 2.9 pully on i dont know what sea level you are at but is it possible you are running rich wait no not if you put a smaller pully on you should be running leaner then more rich right

 

You need a custom tune, mine has never done this, but I don't have a catless DP or the 2.9" pulley on anymore. I just feel like its not worth the risk of putting a smaller puelly on without a tune. Whenever I do get my HPtuner software eventually and my wideband I will put the 2.9" back on, but until then I want to keep my warranty intact. I would say that your spark knocking if its poping before you hit rev limiter..just my .02, get a tune or take the pulley off.